~18% Of Preterm Births (Globally) Are Associated With Exposure To Outdoor Air Pollution

Around 2.7 million preterm births globally in 2010 (around 18% of all preterm births that year) were associated with exposure to outdoor fine-particulate air pollution, according to new research from The Stockholm Environment Institute (SEI) at the University of York.

The new work follows earlier research which suggested that air pollution exposure could be a risk factor for preterm birth (being born at less than 37 weeks gestation). Other known risk factors include: poverty, the mother’s age, illness/disease, and various social factors.

The implications of these new findings are pretty clear — in addition to very negative effect on an individual’s health, on mental abilities, and on worker productivity, particulate air pollution is also strongly associated with preterm births. In other words, yet another reason to try to get the rapidly growing levels of air pollution in the world’s urban centers under control. (It should be noted here that growing levels of internal combustion engine automobile use are a large driver of this increase in urban air pollution levels.)

“This study highlights that air pollution may not just harm people who are breathing the air directly — it may also seriously affect a baby in its mother’s womb,” the lead author of the new study, Chris Malley, commented.

“Preterm births associated with this exposure not only contribute to infant mortality, but can have life-long health effects in survivors.”

Notably, up to 15–18% of births in some African and South Asian countries are now preterm births. Around 4–5% of all births in Europe are now preterm births (this rate used to be much higher, and was one of the reasons that infant mortality rates used to be so much higher).

“A pregnant woman’s exposure can vary greatly depending on where she lives — in a city in China or India, for instance, she might inhale more than 10 times as much pollution as she would in rural England or France,” the press release adds.

“The study did not quantify the risk in specific locations, but rather used the average ambient PM2.5 level in each country, and analysed the results by region. India alone accounted for about 1 million of the total 2.7 million global estimate, and China for about another 500,000. Western sub-Saharan Africa and the North Africa/Middle East region also had particularly high numbers, with exposures in these regions having a large contribution from desert dust.”

Co-author of the new study, Dr Johan CI Kuylenstierna, made an important point: “In a city, maybe only half the pollution comes from sources within the city itself — the rest will be transported there by the wind from other regions or even other countries. That means that often regional cooperation is needed to solve the problem.”

That’s far easier said than done, though. The roughly 50% (obviously, this figure varies greatly by location) that’s being generated within the city itself, though, is a good place to start.